1. Calculating Stair Sizes Including string length Click mouse to bring each point or item in, to work through this example M. S. Martin Randwick TAFE Revised Feb - 2008

2. Calc’s Exercise – Worked Example You may choose to write this down for reference as you work through next slide Specification: Calculate the quantity of timber required for the open riser stair with following spec: –Rise of flight850mm –Going of flight1.100m –String material250mm x 38mm sawn H/W –Treads45mm thick sawn H/W –Width of stair1.200m –Assume rise160mm

3. Answer – note: this symbol √ below means square root No. of Risers =.850.160 =5.312 say 5 risers Height of riser =.850= 170mm 5 No. of Goings = 4 Width of going =1.100 4 =275mm Check 2R + G = 550 to 700 =(2 x 170) + 275 = 615 OK Length of string √ (rise of flight)² + (going of flight + one going of step)² √.850² + (1.100 +.275)² √.850² + 1.375² √.723 + 1.891 √ 2.614 = 1.617 Order 1.8m lengths String 250 x 38 H/W 1 @ 3.6 Treads 275 x 45 H/W 1 @ 4.8 (this size is simply to suit going requirement) You don’t have to show all the working, but for this example it shows you the full answer